Vehicles having a hybrid drive train are well known in the art. They are usually provided with an internal combustion engine (ICE), an electric traction motor that may transmit power to at least one wheel of the vehicle and an electric generator used to supply electricity to the traction motor and/or to recharge batteries of the vehicle.
On the one hand, a hybrid drive train is said to be a series hybrid drive train when the traction motor is used to drive the wheels and the ICE is exclusively used to drive the electric generator to recharge the vehicle's batteries and/or supply electric power directly to the traction motor.
On the other hand, a hybrid drive train is said to be a parallel hybrid drive train when both the traction motor and the ICE may be used simultaneously or individually to drive the wheels of the vehicle. In parallel hybrid drive trains, the ICE may also be used to recharge the batteries through the electric generator.
Series/parallel hybrid vehicles (SPHV) are also known in the art. Conventionally, these vehicles include drive trains that may be switched between a series mode and a parallel mode, as described hereinabove.
Early parallel hybrid drive included electric motors associated with the front wheels and an ICE associated with the rear wheels. This arrangement has the drawback of taking much space in the vehicle.
Often, parallel hybrid drive trains include an interconnection between the ICE, the traction motor and the electric generator. This interconnection is often provided by a planetary gear assembly. A drawback of such an interconnection is its mechanical complexity and inherent inefficiency.